Parametric ISO 4032 Hex Nut Generator

A university studies project exploring parametric CAD generation. It models an ISO 4032 metric hex nut (default M10) in C++20, producing both 3D solid geometry and 2D technical drawings from a single parametric definition.

Features

• ISO 4032:2012 Compliant: Automatic lookup of standard dimensions ($P, d_a, d_w, e, m, m_w, s$) for the metric thread series (M1.6 — M20).
• 3D Solid Geometry: Hex body, ISO 68-1 internal thread, external chamfers and internal countersink built with OpenCASCADE, exported to hex.stl and hex.stp.
• Technical SVG Export:
  • Orthographic views (top and side/section).
  • ISO-standard hatching and line styles (broken circles for thread roots).
  • Automated dimensioning and technical legend.
• Parametric Design: Driven by HexNutParams; easily extendable to other standard sizes or custom geometries.

Project Structure

• src/: C++ source code (main.cpp, HexNutParams.hpp, SVGExporter.hpp).
• docs/: Technical documentation.
  • LaTeX/: Project reports, PDFs, and citations.
• models/: CAD source files, including the FreeCAD model (hex_nut_M10.FCStd).
• cmake-build-debug/: CMake build artifacts.

Requirements

• Compiler: C++20 compatible (uses <numbers>, std::to_array, std::ranges).
• Build System: CMake 4.2+.
• Dependencies:
  • OpenCASCADE (3D modelling kernel). On Linux/macOS (or via vcpkg/conda) it is located with find_package. For the Windows binary distribution, point CMake at the unpacked folder via OpenCASCADE_ROOT (see below).
  • vincentlaucsb/svg (header-only SVG writer, fetched via FetchContent).
  • CLI11 (command-line parsing, fetched via FetchContent).

Configuring OpenCASCADE paths (Windows)

Copy .env.example to .env and set OpenCASCADE_ROOT (and OpenCASCADE_THIRDPARTY_ROOT) to your unpacked distribution folders. The .env file is git-ignored so machine-specific paths stay out of version control. Precedence (highest first): -D<VAR> on the cmake command line > real environment variable > .env > defaults. The data-exchange toolkits are resolved by name, so both pre- and post-7.7 OCCT releases (TKSTEP/TKDESTEP, TKSTL/TKDESTL) work.

Getting Started

1. Build:

   mkdir build && cd build
   cmake ..
   make

2. Run:

   ./cadcam_hex_nut_m10

   With no arguments this generates hex_M10_iso.stl, hex_M10_iso.stp, hex_M10_iso_top.svg, and hex_M10_iso_side.svg in the current directory. Output paths can be overridden with -o/--out-stl, --out-step, --out-svg-top, and --out-svg-side.

3. Parametric options (run with --help for the full list):

   • -d/--diameter — nominal thread diameter (default 10), drives the ISO 4032 lookup.
   • -p/--pitch, -s/--flats, -m/--height, --da, --dw — override individual ISO table values.
   • --theta — internal countersink angle in degrees (default 120).
   • --beta — external chamfer angle in degrees (default 30).
   • --flank-angle — thread flank angle in degrees (default 60).

   When any geometry value is overridden, the auto-generated filenames encode the overrides (e.g. hex_M10_theta90_side.svg) instead of the _iso suffix.

Technical Details

• Coordinate System: Model space uses mm (Y-up), exported to SVG canvas (Y-down) with a default scale of 18 pixels/mm.
• Diameters: D is the basic major (nominal) diameter; the internal thread runs from the minor diameter ($D_1 = D - 2 \cdot \tfrac{5}{8}H$) out to the major.
• Thread Representation: Internal threads follow conventional representation (solid line for minor diameter, thin broken arc for major diameter).
• Section View: The side view is a section cut across the corners ($e$) to align with the top view and accurately show chamfer extents.